// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_APP_LIST_APP_LIST_ITEM_LIST_H_
#define UI_APP_LIST_APP_LIST_ITEM_LIST_H_

#include <stddef.h>

#include <string>

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"
#include "base/observer_list.h"
#include "sync/api/string_ordinal.h"
#include "ui/app_list/app_list_export.h"
#include "ui/app_list/app_list_item_list_observer.h"

namespace app_list {

class AppListItem;

// Class to manage items in the app list. Used both by AppListModel and
// AppListFolderItem. Manages the position ordinal of items in the list, and
// notifies observers when items in the list are added / deleted / moved.
class APP_LIST_EXPORT AppListItemList {
public:
    AppListItemList();
    virtual ~AppListItemList();

    void AddObserver(AppListItemListObserver* observer);
    void RemoveObserver(AppListItemListObserver* observer);

    // Finds item matching |id|. NOTE: Requires a linear search.
    // Generally this should not be used directly, AppListModel::FindItem
    // should be used instead.
    AppListItem* FindItem(const std::string& id);

    // Finds the |index| of the the item matching |id| in |app_list_items_|.
    // Returns true if the matching item is found.
    // Note: Requires a linear search.
    bool FindItemIndex(const std::string& id, size_t* index);

    // Moves item at |from_index| to |to_index|.
    // Triggers observers_.OnListItemMoved().
    void MoveItem(size_t from_index, size_t to_index);

    // Sets the position of |item| which is expected to be a member of
    // |app_list_items_| and sorts the list accordingly. If |new_position| is
    // invalid, move the item to the end of the list.
    void SetItemPosition(AppListItem* item, syncer::StringOrdinal new_position);

    // Highlights the given item in the app list. If not present and it is later
    // added, the item will be highlighted after being added.
    void HighlightItemInstalledFromUI(const std::string& id);

    AppListItem* item_at(size_t index)
    {
        DCHECK_LT(index, app_list_items_.size());
        return app_list_items_[index];
    }
    const AppListItem* item_at(size_t index) const
    {
        DCHECK_LT(index, app_list_items_.size());
        return app_list_items_[index];
    }
    size_t item_count() const { return app_list_items_.size(); }

private:
    friend class AppListItemListTest;
    friend class AppListModel;

    // Returns a unique, valid StringOrdinal immediately before |position| or at
    // the end of the list if |position| is invalid.
    syncer::StringOrdinal CreatePositionBefore(
        const syncer::StringOrdinal& position);

    // Adds |item| to the end of |app_list_items_|. Takes ownership of |item|.
    // Triggers observers_.OnListItemAdded(). Returns a pointer to the added item
    // that is safe to use (e.g. after releasing a scoped ptr).
    AppListItem* AddItem(scoped_ptr<AppListItem> item_ptr);

    // Finds item matching |id| in |app_list_items_| (linear search) and deletes
    // it. Triggers observers_.OnListItemRemoved() after removing the item from
    // the list and before deleting it.
    void DeleteItem(const std::string& id);

    // Removes the item with matching |id| in |app_list_items_| without deleting
    // it. Returns a scoped pointer containing the removed item.
    scoped_ptr<AppListItem> RemoveItem(const std::string& id);

    // Removes the item at |index| from |app_list_items_| without deleting it.
    // Returns a scoped pointer containing the removed item.
    scoped_ptr<AppListItem> RemoveItemAt(size_t index);

    // Deletes item at |index| and signals observers.
    void DeleteItemAt(size_t index);

    // If |item|->position() is not a valid ordinal, sets |item|->position()
    // to a valid ordinal after the last item in the list.
    void EnsureValidItemPosition(AppListItem* item);

    // Returns the index at which to insert an item in |app_list_items_| based on
    // |position| (which must be valid) and |id| (if the positions are equal).
    size_t GetItemSortOrderIndex(const syncer::StringOrdinal& position,
        const std::string& id);

    // Fixes the position of the item at |index| when the position matches the
    // previous item's position. |index| must be > 0.
    void FixItemPosition(size_t index);

    ScopedVector<AppListItem> app_list_items_;
    base::ObserverList<AppListItemListObserver, true> observers_;
    std::string highlighted_id_;

    DISALLOW_COPY_AND_ASSIGN(AppListItemList);
};

} // namespace app_list

#endif // UI_APP_LIST_APP_LIST_ITEM_LIST_H_
